A technique for calculating a positional attitude of a camera based on features (i.e., natural feature points or markers) appearing on an image captured by the camera is widely used in a mixed reality (MR) system or an augmented reality (AR) system.
Generally, precision of the positional attitude of the camera calculated by the above-described technique is fluctuated by the arrangement status of features in a scene. Thus, in order to calculate the positional attitude of the camera with desired precision, arrangement of the features needs to be previously adjusted so that calculation precision of the positional attitude of the camera is improved. However, it is difficult for a user to determine the arrangement of features that can improve the calculation precision of the positional attitude of the camera.
Therefore, a technique for assisting an operation of arranging the features has been developed in order to improve the calculation precision of the positional attitude of the camera. The patent literature 1 (PTL 1) discusses a technique for assisting arrangement of markers (i.e., printed materials in which identifiers are coded into predetermined geometric patterns) when a camera positional attitude is to be estimated by using the markers as features. According to the technique, a spatial region where the camera positional attitude can be calculated with high precision in the current marker arrangement is visualized. While checking the spatial region where the camera positional attitude can be calculated with high precision, a user interactively adds a marker so that the spatial region covers a desired region.